Core Location: Techniques
As far as using the main knuckle, think about how we pick things up. Can we effectively pick up anything effectively with the upper finger joints?
When picking there are two types of strokes [free and rest] , while the motor driver remains the same (the main knuckle of each finger). A free stroke is when the tip of the finger goes towards the palm of the hand and doesn't land on the string above the string being plucked. A rest stroke is when the tip of the finger lands on the string above the string being plucked. Where the fingertip lands is based on the position of the hand. We use the same knuckle to pluck, while the fingertip "lands" in a different place. For a free stroke, the main knuckle is above the string being plucked. For a rest stroke, the main knuckle is roughly 3 strings above the string being plucked. Experiment with the position of the picking hand and angles.
Again, the main driver for fingerpicking is the main knuckle where the finger joins the hand. This offers us rebound. When we pluck with this joint, the finger will return to its position. If we are getting ready to pluck a different string, we move your arm to get a different fingertip location.
When we use the main knuckle driver, it automatically snaps back to where it was before [this is called rebound]. Rebound is automatic and is built into our hands [when using the primary driver = the other knuckles have a slower, less reliable recoil].
This is how we track where our fingertips are located. We pluck and forget about the rebound [a single blip of thought completes a whole stroke cycle]. It happens naturally. To pick different strings, we move our arm, which moves our hand. We keep the motion consistent for any string. Same stroke, different arm position.